Application of the gas-phase reactivity of Pb2+ ions to the structural characterization of disaccharides

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Application of the gas-phase reactivity of Pb2+ ions to the structural characterization of disaccharides

Jean-Yves Salpin, Marie Lafitte, Jeanine Tortajada

To cite this version:

Jean-Yves Salpin, Marie Lafitte, Jeanine Tortajada. Application of the gas-phase reactivity of Pb2+ ions to the structural characterization of disaccharides. 16th International Mass Spectrometry Con-ference, 2003, Edimbourg, United Kingdom. 2003. �hal-00069114�

Laboratoire Analyse et Environnement – UMR CNRS 8587

Bâtiment des Sciences - Université d’Evry Val d’Essonne - Boulevard François Mitterrand - 91025 Evry Cedex - France

• Oligosaccharide analysis is a challenging task for mass spectrometry. A complete structural description of carbohydrates implies notably exact mass measurement, sites and anomeric configuration of the glycosidic linkages, and also stereochemical characterization of the different asymmetric centers of the sugar ring. Many studies have been carried out on those topics for more than three decades. With the advent of soft ionization techniques, it has been shown that structural isomers can be differentiated when coordinated to certain metal ions. Lead cationization has proven to be particularly useful is the structural differentiation of monosaccharides.(1) _{The present study aims to examine if the lead}

reactivity can be also used to characterize the glycosidic linkage. To this end the results obtained with a series of disaccharides are presented.

• Triple-quadrupole mass spectrometer (Applied Biosystems MDS/SCIEX API2000) fitted with a "TurboIonspray" source.



Mass Spectrometry

Molecular orbital calculations

• MS/MS experiments with N₂ as collision gas (P  2 10-5 _{Torr ).}



Introduction

• Aqueous solutions of Pb(NO₃)₂/disaccharide (5.10-5 _mol.L-1_/10-4 _mol.L-1_).

• Flow rate : 5l/min.

Application of the gas-phase reactivity of Pb

2+

ions to the

structural characterization of disaccharides

Jean-Yves Salpin, Marie Laffite, Jeanine Tortajada

• Preliminary step : PM3 semi-empirical calculations in order to locate the best coordination sites (residues in their 4_C

1 conformation).

• DFT calculations with the B3LYP hybrid functional. Geometry opitimization and vibrational analysis at the B3LYP/6-31G(d,p) level.

• Stuttgart basis set and quasi-relativistic pseudo-potential to describe Pb atom.



Positive ion electrospray spectra

• NBO analysis.

• Three series of ions observed : - PbOH+_.xH

2O (x=0-5; m/z 225, 243, 261, 279, 297 and 315).

- [Pb(disaccharide)_n]2+ _{(n=1-6; m/z 275, 446, 617, 788, 959,1130).}

- [Pb(disaccharide)_m – H]+ _{(m=1-2; m/z 549, 891).}



MS/MS spectra of [Pb(disaccharide) – H]

_{(m/z 549)}

Name type Parent ion Fragment ions

m/z 549 m/z 489 m/z 459 m/z 429 m/z 387 m/z 369 m/z 351 m/z 327 m/z 309 m/z 297 m/z 279 m/z 267 D-trehalose 1,1- glc glc 24.9±0.9 23.2±1.6 6.6±1.0 100 7.3±0.9 3.3±0.5 12.2±1.1 39.7±2.0 D-neotrehalose 1,1- glc glc 25.6±0.9 42.4±1.8 5.3±0.4 100 3.1±0.2 13.2±0.7 D-kojibiose 1,2- glc glc 25.2±1.1 63.7±4.1 100 35.5±1.4 38.5±2.6 39.3±2.7 5.3±0.7 14.3±1.5 69.5±3.9 D-Sophorose 1,2- glc glc 25.5±1.3 63.7±2.9 100 4.0±0.7 10.1±0.6 5.6±0.6 3.7±0.5 6.4±0.6 24.8±1.8 D-Nigerose 1,3- glc glc 24.9±1.2 27.5±2.7 4.1±1.2 19.7±1.9 38.0±2.6 16.1±1.9 100 20.9±2.0 66.0±4.0 19.5±1.8 78.8±3.2 D-turanose 1,3- glc fru 24.8±0.9 100 17.9±0.6 31.7±0.8 7.5±0.3 38.0±0.7 4.6±0.2 34.8±1.4 2.4±0.2 10.4±0.5 D-Laminaribiose 1,3- glc glc 24.6±1.0 9.6±1.1 21.3±0.8 11.0±1.2 97.0±2.8 5.3±0.8 89.3±5.4 17.3±2.1 33.1±3.6 35.2±4.6 100 D-maltose 1,4- glc glc 26.1±0.9 24.0±1.0 100 14.6±0.1 49.6±1.8 9.9±0.5 14.1±1.0 6.0±0.5 13.4±0.9 8.8±0.8 D-maltulose 1,4- glc fru 25.1±1.0 4.0±0.1 29.3±1.6 57.6±1.3 44.9±1.6 8.2±0.5 53.9±1.7 9.2±0.4 100 4.7±0.3 19.0±0.7 D-cellobiose 1,4- glc glc 26.0±1.2 14.5±0.7 100 19.4±0.7 57.9±1.9 31.8±1.2 6.7±0.6 7.3±0.8 -D-lactose 1,4- gal glc 25.2±0.8 16.9±0.9 3.1±0.3 100 45.4±2.1 38.3±2.1 31.5±1.4 10.8±0.9 4.1±0.5 13.1±0.7 D-leucrose 1,5- glc fru 24.7±0.9 4.4±1.0 15.0±0.7 36.2±2.2 39.2±3.2 13.2±1.2 19.3±1.2 26.2±2.1 100 15.3±1.3 48.4±3.1 D-palatinose 1,6- glc fru 24.8±0.8 3.0±0.3 78.4±2.8 18.3±1.2 3.4±0.4 78.3±3.4 31.9±1.8 12.0±0.7 7.4±0.6 100 15.4±0.7 84.5±3.1 D-isomaltose 1,6- glc glc 24.8±0.8 29.7±3.1 34.9±3.2 85.4±4.3 6.4±1.4 100 35.1±1.6 27.5±3.0 36.6±3.9 36.3±1.5 13.4±1.3 57.8±5.4 D-mellibiose 1,6- gal glc 25.1±1.2 46.3±2.3 63.5±3.6 100 26.0±1.9 79.1±4.9 15.0±0.7 58.1±3.7 4.7±0.6 9.6±1.1 D-gentiobiose 1,6- glc glc 24.8±0.8 24.8±1.6 9.6±1.0 66.8±3.3 4.4±0.6 100 15.7±0.7 3.3±0.4 5.9±0.7 13.1±0.7 200 250 300 350 400 450 500 550 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 327 267 549 387 279 309 ₃₆₉

• Residual intensity of the parent ion set to 25 % by varying the collision energy, all the other parameters being kept constant.

• MS/MS spectra repeated 10 times for each disaccharide to check the reproducibility of the intensities.

• The results are summarized below (peaks with relative abundances below 3 % are not taken into account).

• All the disaccharides present similar positive ion electrospray spectra.

• [Pb(disaccharide)_m – H]+ _{species come from dissociative proton transfer within the doubly charged complexes .}

• Structural distinction of the disaccharides based on the MS/MS spectra of the [Pb(disaccharide) – H]+ _{ion (m/z 549).}

D-trehalose  (11) glc-glc 200 250 300 350 400 450 500 550 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 267 429 309 ₃₂₇ 351 549 279 321 225 368 369 D-Kojibiose  (12) glc-glc 200 250 300 350 400 450 500 550 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 327 267 297 369 459 ₅₄₉ 387 309 279 ₃₅₁ 281 225 _{321 429} D-Nigerose  (13) glc-glc 200 250 300 350 400 450 500 550 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 429 369 549 489 327 387 297 ₃₅₁ 267 D-maltose  (14) glc-glc D-isomaltose  (16) glc-glc 200 250 300 350 400 450 500 550 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 369 429 267 351 ₄₅₉ 297 ₄₈₉ 327 549 279 387 225 ₃₂₁ 459 200 250 300 350 400 450 500 550 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 297 267 369 351 309 549 429 279 327 225 387 D-Palatinose  (16) glc-fru 200 250 300 350 400 450 500 550 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 297 387 327 369 429 549 267 309 ₃₅₁ 279 459 489 D-maltulose  (14) glc-fru 200 250 300 350 400 450 500 550 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 459 327 297 ₃₆₉ 549 387 267 ₃₅₁ 309 D-turanose  (13) glc-fru



Results



Conclusion



Perspectives

• Three types of fragmentations are observed :

- cross-ring cleavages associated with the elimination of C_nH_2nO_n molecules. The most informative are those occuring at the reducing ring.

- glycosidic bond cleavages giving rise to m/z 387 and m/z 369 ions. These fragments may correspond to Y₁(2) _{or C}

1, and to B1 or Z1, respectively.

- successive dissociation of m/z 387 and 369 giving rise to numerous fragments in the m/z 200-387 range.

• The gas-phase reactivity of Lead(II) ions allows :

- the unambiguous location of the position of the glycosidic bond for both homodimers (glc-glc) and heterodimers (glc-fru) (cross ring cleavages, m/z 387/m/z 369 abundance ratio).

- The determination of the nature of the second residue (glucose vs fructose), notably thanks to the secondary fragmentations. These secondary fragmentations also give some insight concerning the structures of m/z 387 and 369 ions for the glc-fru series. Indeed, based on our study dealingbwith the monosaccharides(1)_{, an intense m/z 297 is the signature of a complex [Pb(fructose)-H]}+ _{ion losing C}

3H6O3.

This suggests that m/z 387 and 369 ions might correspond to Y₁ and B₁ ions.

- H + Pb + O HO OH OH OH O OH OH CH₂ O HO OH Y₁ Z₁ B₁ C₁ m/z 387 m/z 387 m/z 369 m/z 369 0,2_A 2 0,2_X 2



Bibliography

DFT study

- the characterization of the anomericity of the first residue.

- the distinction between pyranosic and furanosic form of the fructose residue (comparison D-leucrose/D-palatinose)

• As already observed for the Pb/monosaccharide system, the most stable [Pb(disaccharide) –H]+ _{complexes involve deprotonation of a}

hydroxymethyl group, interaction with a hemiacetal oxygen, and the glycosidic oxygen (when accessible).

• Assuming this particular bonding scheme, deprotonation of either the first or the second monosaccharide unit leads to nearly degenerated structures. Consequently, fragmentations may indifferently occur on each residue.

D-cellobiose D-maltose

D-palatinose

• NBO analysis : net charge of Pb 1.43

natural electronic configuration of Pb [core]6s(1.93)6p(0.63)sp0.33

Pb(II) lone pair : 6p contribution of 3 to 4 %

B3LYP/6-31G(d,p)

• Analysis of bigger oligosaccharides.

(1) J-Y. Salpin, J. Tortajada,

J. Mass Spectrom.

Glycoconjugate J.

• Lead cationisation combined with MS/MS experiments induces fragmentations which provide very useful information about the glycosidic linkage position and the nature of the residues.

• Isotopic labeling experiments are in progress in order to examine in detail the mechanisms of fragmentation. D-Laminaribiose 544 548 552 m/z, amu 549 548 545 274 278 m/z, amu 279 275 274 281 400 600 800 1000 m/z, amu 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Rel. Int. (%) 261 243 279 ₅₄₉ 446 275 297 ₆₁₇ 788 891 959 ₁₁₃₀



Methodology